SECTOR_SIZE
memcpy(sc->io_data, sc->bounceb, SECTOR_SIZE);
sc->io_data += SECTOR_SIZE;
sc->io_bytes -= SECTOR_SIZE;
toff = sec * SECTOR_SIZE;
tsz = sc->nsectors * sc->nheads * SECTOR_SIZE;
lp->d_secsize = SECTOR_SIZE;
sc->bounceb = alloc_stmem(SECTOR_SIZE, &addr);
if (bp->b_blkno < 0 || (bp->b_bcount % SECTOR_SIZE) != 0) {
sz = howmany(bp->b_bcount, SECTOR_SIZE);
memcpy(sc->bounceb, sc->io_data, SECTOR_SIZE);